A Fragility Framework for Surface Erosion with Application to Earthen Dam Breaching: Resources

Overtopping failures of earthen dams are a growing concern under intensifying extreme rainfall. This study introduces a probabilistic fragility framework that combines hydrologic modeling, hydraulic analysis, and soil erodibility to assess erosion risk under uncertain load and resistance. Fragility curves derived from Monte Carlo simulations quantify erosion initiation and severity as functions of rainfall depth and excess shear stress. Application to multiple dams affected during the 2015 South Carolina floods reproduces observed outcomes ranging from complete breach to no damage. The framework also captures cascading effects, where failure of an upstream structure increases downstream loading and erosion potential. Compared with deterministic approaches, the method better represents outcome variability and provides a more reliable basis for dam safety assessment and flood risk mitigation.

在极端降雨事件愈发频发的背景下，土坝漫顶溃决已成为日益受到重视的安全问题。本研究提出了一种融合水文模拟（hydrologic modeling）、水力分析（hydraulic analysis）与土壤可蚀性（soil erodibility）分析的概率性易损性框架（probabilistic fragility framework），用于在荷载与抗力存在不确定性的条件下开展侵蚀风险评估。基于蒙特卡洛模拟（Monte Carlo simulations）得到的易损性曲线，以降雨深度与超额剪应力（excess shear stress）为自变量，量化了侵蚀起始阈值与侵蚀严重程度。将该框架应用于2015年南卡罗来纳州洪灾中受影响的多座土坝，模拟结果与观测到的从完全溃决到无损的各类灾情均保持一致。该框架还可捕捉级联效应（cascading effects）：上游构筑物发生溃决后，会增大下游的荷载负荷与侵蚀潜在风险。相较于确定性分析方法（deterministic approaches），本方法能够更精准地刻画灾情结果的变异性，可为土坝安全评估与洪水风险减灾提供更为可靠的决策支撑。